<template>
    <div class="selection-component">
      <div class="selection-show" @click="toggle"> 
        <span>{{ selection[nowIndex].label }}</span>
        <div class="arrow"></div>
      </div>
      <div class="selection-list" v-if="isDrop">
        <ul>
          <li 
            v-for="(item, index) in selection" 
            :key="index"
            @click="chooseSelect(index)"
          >
          {{ item.label }}  
          </li>
        </ul>
      </div>
    </div>
</template>

<script>
export default {
  props: {
    selection: {
      type: Array,
      default: [{
        label: 'test',
        value: 0
      }]
    }
  },
  data() {
    return {
      isDrop: false,
      nowIndex: 0,
    }
  },
  methods: {
    toggle() {
      this.isDrop = !this.isDrop
    },
    // 选中时收起下拉框，并选中当前项
    chooseSelect(index) {
      this.nowIndex = index;
      this.isDrop = false;
      // 将当前选中的项传出去给后端
      this.$emit('on-change', this.selection[this.nowIndex])
    }
  }
}

</script>

<style scoped>
.selection-component {
  position: relative;
  display: inline-block;
}
.selection-show {
  border: 1px solid #e3e3e3;
  padding: 0 20px 0 10px;
  display: inline-block;
  position: relative;
  cursor: pointer;
  height: 25px;
  line-height: 25px;
  border-radius: 3px;
  background: #fff;
}
.selection-show .arrow {
  display: inline-block;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  border-top: 5px solid #e3e3e3;
  width: 0;
  height: 0;
  margin-top: -1px;
  margin-left: 6px;
  margin-right: -14px;
  vertical-align: middle;
}
.selection-list {
  display: inline-block;
  position: absolute;
  left: 0;
  top: 25px;
  width: 100%;
  background: #fff;
  border-top: 1px solid #e3e3e3;
  border-bottom: 1px solid #e3e3e3;
  z-index: 5;
}
.selection-list li {
  padding: 5px 15px 5px 10px;
  border-left: 1px solid #e3e3e3;
  border-right: 1px solid #e3e3e3;
  cursor: pointer;
  background: #fff;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;

}
.selection-list li:hover {
  background: #e3e3e3;
}
</style>
